This is a request for renewal of a T32 training program from the Department of Pediatrics at Vanderbilt University School of Medicine. Our long term objective is to support the career development of pediatric physician-scientists who will become the future leaders in child health research in vulnerable populations. Such populations include children who are at risk for adverse health outcomes due to intrinsic biologic differences, elevated burdens of disease, or social characteristics such as financial limitations, place of residence, and inability to communicate effectively. The specific aims of this proposal are to identify qualified trainees at the end of residency or early in fellowship training and to provide them with an interdisciplinary research experience in the laboratory of a qualified mentor with adequate resources and space and ready access to unique populations of vulnerable children. To ensure long term success, this experience will be integrated with the Vanderbilt Master of Science in Clinical Investigation and Master of Public Health programs, an applied skills practicum in conducting research in vulnerable populations, and frequent interactions among trainees from multiple disciplines to foster trainees' career development. Highlights since the program was funded in May 2009 include the training of 15 young physician-scientists from neonatology, pediatric infectious diseases, pediatric hematology/oncology, developmental pediatrics, general pediatrics, pediatric cardiology, and pediatric endocrinology. Nine fellows have completed the program, 100% entered into additional research training or academic careers at the end of training. After two fellows left academics for personal reasons during the two years following training, the program modified selection criteria and to date 100% of the more recent graduating fellows remain in academics. The trainees have published 63 manuscripts (4.2 per trainee) and the program's diversity efforts have been quite successful (27% of the trainees came from underrepresented groups). In view of the continued strong applicant pool and the strengths of the program, we propose continued support for three trainees in PGY-5 and three in PGY-6. The program director will utilize an Advisory committee composed of national experts within and external to Vanderbilt University to obtain on-going advice with respect to candidate and mentor selection, scholarly progress of selected candidates and overall success. The proposal is broadly focused within four core disciplines that represent unique and substantial research strengths of Vanderbilt University and that define critical areas of need for new knowledge in child health research on particularly vulnerable populations and include Infectious Diseases/Epidemiology, Neurodevelopment, Health Disparities, and Pharmacoepidemiology/Pharmacogenomics. Continuation of this program will permit the development of a cadre of highly-qualified pediatric physician-scientists with the skills, knowledge and dedication to solve some of the most important health care issues currently facing our nation's children.